We will continue to study the role, in differentiation, of developmentally regulated lectins in cellular slime molds and embryonic chick tissues. We will specifically continue to test the hypothesis that lectins that appear on the surface of cells as they differentiate play a role in specific cellular interaction. Using lectins purified from three species of cellular slime mold and three developing chick organs, and antibodies to these lectins, we will attempt to influence intercellular associations, thereby learning something about the function of these carbohydrate-binding proteins. We will also seek complementary oligosaccharide receptors for these proteins.